I highly recommend the book Here, There and Everywhere, written by Geoff Emerick if you are interested in all the details of how they recorded and the things they did in the studio that was completely different from the norm of those days in time. They paved the way for most of the things that we take for granted today.
I remember reading something about John wanting to place a live mic underwater during either the Yellow Submarine's sessions or Octopus's Garden sessions and they stopped him before he electrocuted himself.
Another interesting technique was wiring up a guitar speaker to act as a microphone, to capture sound rather than push sound. Just really interest stuff through out this book, as well as plenty of discussion on how they interacted with one another and went about their work. I need to read it again, in fact. There is just so much to absorb.